A disk drive or direct access storage device ("DASD") includes one or more disks stacked on a spindle. The surface of each disk is allocated into concentric tracks where data is stored. The disks may be made of a variety of materials. Most commonly, the disks are made of metal, glass or plastic. Storage of data on these disks entails magnetizing portions of the disk in a pattern which reflects the data.
In order to magnetize tiny areas of the surface of a disk, a small ceramic element called a slider which contains a magnetic transducer known as a write head is passed over the surface of the disk. More specifically, when operating at full speed the write head typically is flown at a height of approximately one to two millionths of an inch from the surface of the disk and is flown over the track as the write head is energized to various states causing the track on the disk below to be magnetized to represent the data to be stored. During startup and shutdown processes, when the disk is either not rotating or is rotating too slowly to provide the air bearing, the slider will be in contact with the disk. Shock events can also cause the slider to contact the disk.
To retrieve data stored on a magnetic disk, the slider, which also contains a read head, is flown over the disk. The magnetized portions of the disk induce a current in the read head. By looking at output from the read head, the data can be reconstructed for use by the computer system. Typically, the same ceramic block contains both a read head and a write head.
Like a record, both sides of a disk are generally used to store data or other information necessary for the operation of the disk drive. Since the disks are held in a stack and are spaced apart from one another, both the top and the bottom surface of each disk in the stack of disks has an associated slider.
To meet the ever-increasing density requirements of magnetic data storage devices, such as the disk drives, major emphasis has been placed on reducing the spacing between the head and the disk. The spacing loss is regarded as the most severe limitation in achieving higher density magnetic storage. To minimize the spacing between the head and the disk, the conventional hard disk drive utilizes an air-bearing technique to fly the head very close to the disk. To ultimately eliminate entirely the spacing between head and disk, contact recording for the disk drive has been proposed.
The REED head structure is one contact recording scheme known in the industry. The REED head structure is an integrated transducer/slider/suspension design that replaces the suspension assembly discussed above. Basically, it is a long, thin rod, known as a "reed," made of thick film aluminum oxide (Al.sub.2 O.sub.3). Within it, there are conductor leads, as well as magnetic transducers (read/write heads). Because it is a lightweight, integrated structure, the REED head can remain in contact with the magnetic disk at all times. The critical component of the REED head structure is the wear lifetime of the contact wear pad(s).
In the first attempt to achieve a wear-resistant head, sputtered aluminum oxide (Al.sub.2 O.sub.3) was used as a contact wear pad in the REED head structure. However, it has been determined that the wear rate of Al.sub.2 O.sub.3 is considerably faster than desired. Carbon and various carbonaceous materials have been disclosed for use as the protective layer for magnetic media surfaces, but when deposited to a useful thickness these materials will not adhere properly to substrate materials used for sliders.